This is my connection diagram of my net

I can ping with all users except on brigde3, from 10.0.0.1 ping to 10.0.0.3 but NOT to 10.0.0.6
From 10.0.0.3 I can ping with all
From 10.0.0.6 I only see brigde3
What’s the problem??? Why can’t I work Ips on brigde3 but I can see their MAC???
Thank you
RB450G

RB433AH (same in both)
